5G cm Wave vs. mm Wave: Key Differences Explained
By RF Wireless Expert Team
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This article explores the differences between 5G centimeter wave (cm wave) and millimeter wave (mm wave) technologies. We’ll delve into the key characteristics of each, providing a clear comparison to help you understand their respective strengths and weaknesses.
The table below summarizes the key distinctions between 5G variants, including sub-6 GHz, cm wave, and mm wave. As the names suggest, cm wave refers to wavelengths in the centimeter range, while mm wave operates with wavelengths in the millimeter range.
Comparison Table: 5G Sub-6 GHz vs. cm Wave vs. mm Wave
| Features | 5G sub 6GHz | 5G cm wave | 5G mm wave |
|---|---|---|---|
| Frequency spectrum | 0.5 to 10 GHz | 3 to 30 GHz | 30 to 100 GHz |
| Bandwidth | approx. 5 to 40 MHz | approx. 40 to 200 MHz | approx. 400 to 2 GHz |
| Duplex topology | FDD/TDD | Dynamic TDD | Dynamic TDD |
| Transmit power(DL/UL) | >40dBm/ 23 dBm | <approx. 30dBm/23 dBm | <approx. 30dBm/23 dBm |
| Modulated waveform (DL/UL) | OFDMA/SC-FDMA | OFDMA/OFDMA | SC-TDMA/SC-TDMA |
| Multiple Access Type | Time and Frequency | Time and Frequency | Time |
| Multi Antenna technique | SU/MU Beamforming and Medium Rank | SU/MU Beamforming and High Rank | SU/MU Beamforming and Low Rank |
| TTI (Transmission Time Interval) | Flexible | Approx. 0.25 ms | Approx. 0.1 ms |
Source: 5G Research at Nokia Networks
Key Takeaways from the Table:
- Frequency Spectrum: mmWave utilizes a much higher frequency spectrum (30-100 GHz) compared to cmWave (3-30 GHz) and sub-6 GHz. This higher frequency allows for significantly greater bandwidth.
- Bandwidth: The wider frequency spectrum translates directly to significantly higher bandwidth for mmWave, offering the potential for much faster data speeds.
- Transmit Power: cmWave and mmWave generally operate at lower transmit power compared to sub-6 GHz.
- TTI (Transmission Time Interval): mmWave has the shortest TTI, which contributes to lower latency.